1. Field of the Invention
The present invention concerns the insertion of components designed to form the active part of so-called chip cards.
2. Description of the Prior Art
Chip cards, which most usually have a credit card format of a few centimeters square with a thickness of about 1 or 2 millimeters, are most often manufactured as follows: to begin with, an integrated circuit chip is soldered to a small printed circuit formed by an insulating film (made of polyimide for example) coated with etched conductors. The chip is soldered by its rear face to a conductive zone of the printed circuit, and connecting wires are soldered between contacts of the chip and other conductive zones of the printed circuit. Then the chip and the printed circuit are coated with a thermoplastic protective insulating resin (epoxy resin), while letting conductive zones, which will subsequently be used as contacts for access to the integrated circuit when it is incorporated in a card, to project beyond this coating. Thus, what is called a micromodule, containing an integrated circuit chip and its access contacts, is made. It is this micromodule that has to be inserted in a credit card format card.
In the inserting operation, the micromodule is placed in a cavity formed in a card made of plastic material (polyvinyl chloride) and then the plastic material of the card is made to adhere to the thermoplastic resin coating the micromodule, for example by using a spot of bonder between these two elements. The micromodule gets solidly joined to the card, and the assembly is over.
It has been noted, however, that the adhesion is not as lasting as might be wished. This is true especially for cards intended for intensive use by the general public. Indeed, cards intended for use by the general public are often handled without much care and they may happen to undergo exaggerated twisting, bending and other stresses. Moreover since the public wishes these cards to take up as little space as possible and, preferably, to be as flat as possible so that they can be easily slipped into wallets, it is even more difficult for the cards to withstand these bending and twisting stresses.
Experience shows that the micromodule of the chip card tends to get separated following repeated bending of the card which makes it unusable because it can no longer be inserted conveniently in card readers.
This is why the invention proposes a new method for the fabrication of cards which not only has the advantage of increasing resistance to stresses, especially resistance to the loosening of the micromodule but is also very easy to use.